I purchased a duplex in WI last mo. and inherited bad tenants...

[James Howe]

Hi all, I am in need of some guidance, please. Any direction is much appreciated.

I purchased a duplex in Jan 2018 in Burlington, WI and inherited some bad tenants in the upper unit. Their existing lease with the former landlord prohibited pets, prohibited smoking in the unit, and prohibited unauthorized persons living in the unit.  

I've since learned the following about these tenants...

1) They have 5 small dogs!

2) I have photo evidence of cigarette butts in the unit and communal basement

3) They have adults living in the unit that are not on the lease no approved of by myself or the former Landlord.

4) They owe the former landlord 3 mo of back rent and have not paid me yet for Feb 2019

5) The tenants have now gone silent...they are not returning texts or phone calls

Based upon the above violations, do I, as the new Landlord have the right to terminate the existing lease made between tenant and the former Landlord? If so, do I have to issue a "X Day Notice to Vacate"? Or do I have to honor the existing lease and proceed with eviction?

Thanks for taking the time to help. Much appreciated.

James Howe